In recent years, a magneto-optical recording medium has been widely used as a rewritable magneto-optical recording medium. In the magneto-optical recording medium, information is recorded and reproduced by converging a light beam from a semiconductor laser onto the magneto-optical recording medium. However, such magneto-optical recording medium has a drawback in that when a recording bit diameter and an interval between the recording bits are smaller with respect to a diameter of the light beam, reproducing characteristics deteriorate. The described problem occurs for the following reason. As the adjoining recording bits fall within the diameter of spot of the laser beam on the target recording bit, it is not possible to reproduce each recording bit separately.
In order to solve the above-mentioned problem, Japanese Unexamined Patent Publication No. 150418/1994 (Tokukaihei 6-150418) discloses a magneto-optical recording medium including a reproducing layer which has in-plane magnetization at room temperature and in which a transition from the in-plane magnetization to perpendicular magnetization occurs with a temperature rise, a recording layer having perpendicular magnetization for recording information, and a nonmagnetic intermediate layer formed between the reproducing layer and the recording layer wherein the reproducing layer and the recording layer are magnetostatically coupled.
In the described magneto-optical recording medium, information recorded in a recording magnetic domain of a portion in the reproducing layer having the in-plane magnetization is not reproduced, namely, this portion is masked. According to the above arrangement, even in the case where a plurality of recording bits fall within a diameter of a spot of the laser beam converged onto the reproducing layer, an individual recording bit is reproduced separately, provided that the power of the light beam and the temperature at which the reproducing layer has the perpendicular magnetization are appropriately set, thereby achieving a high density recording bits.
However, the magneto-optical recording medium disclosed in the above-mentioned Japanese Unexamined Patent Publication No. 150418/1994 (Tokukaihei 6-150418) have such drawback that in the case where recording and reproducing are carried out on a magneto-optical recording medium having a smaller recording bit diameter and an smaller interval between the recording bits, it is not possible to obtain reproducing signal as a result of insufficient masking of the reproducing layer having the in-plane magnetization.